Tilting pad thrust bearings typically transmit a thrust force from a rotating shaft to a ring of bearing pads via a hydrodynamically generated film between the individual bearing pads and the cooperating collar (or runner), which rotates with the shaft. The thickness of this film depends on many factors, and may be less than five microns in certain applications.
It is important that all individual bearing pads lie in the plane of the collar due to the small film thickness between the bearing pads and the collar. Generally, this requires that the parts of the tilting pad bearing are machined to very high tolerances, and that the machine build results in an accurate alignment between the plane of the collar and the bearing support (to which a tilting pad bearing is affixed). Accurate alignment of the relevant elements becomes more difficult as the size of the machine increases.
Several tilting pad bearings of the prior art have disclosed mechanisms between the bearing pads and the bearing support designed to compensate for the above-mentioned difficulties. A partial solution for small tilting pad thrust bearings was disclosed in GB 1,140,773, which taught filling a sealed chamber between two axially spaced annular plates with a fluid. Accordingly, each plate could move angularly with respect to the other but resist any change in the mean axial position with respect to one another due to the fluid interface. Manufacturing considerations limit the use of this type of tilting pad bearing to machines requiring a bearing with an outside diameter of up to approximately 200 millimeters.
A similar device was taught by in GB 1,458,660 that used individual capsules, each constructed in a manner similar to that of the joined annular plates described above, wherein each capsule carried one bearing pad. The capsules were set in a ring housing and fluidly connected via a series of hydraulic pipes. However, the associated connections and piping increased the likelihood of a hydraulic leak exponentially compared to other systems.